Professor Stewart Clark's Outputs (190)

On the identification of the oxygen vacancy in HfO(2) (2011)
Journal Article
Clark, S., Lin, L., & Robertson, J. (2011). On the identification of the oxygen vacancy in HfO(2). Microelectronic Engineering, 88(7), 1464-1466. https://doi.org/10.1016/j.mee.2011.03.078

The single positively charge oxygen vacancy in HfO2 is found to undergo a symmetry breaking distortion to a C2v symmetry, driven by electron localization, which is consistent with the experimentally observed electron spin resonance signal. This compl... Read More about On the identification of the oxygen vacancy in HfO(2).

Characterisation of the GAG-binding properties of complement factor H, an immune regulator associated with AMD (2011)
Journal Article
Clark, S., Herbert, A., Uhrin, D., Hakobyan, S., Morgan, B., Bishop, P., & Day, A. (2011). Characterisation of the GAG-binding properties of complement factor H, an immune regulator associated with AMD. International Journal of Experimental Pathology, 92(3), A37-A38

Ab initio transition state searching in complex systems: Fatty acid decarboxylation in minerals (2011)
Journal Article
Geatches, D., Greenwell, H., & Clark, S. (2011). Ab initio transition state searching in complex systems: Fatty acid decarboxylation in minerals. The Journal of Physical Chemistry A, 115(12), 2658-2667. https://doi.org/10.1021/jp200106x

Because of the importance of mineral catalyzed decarboxylation reactions in both crude oil formation and, increasingly, biofuel production, we present a model study into the decarboxylation of the shortest fatty acid, propionic acid C2H5COOH, into an... Read More about Ab initio transition state searching in complex systems: Fatty acid decarboxylation in minerals.

Calculation of infrared and Raman vibration modes of magnesite at high pressure by density-functional perturbation theory and comparison with experiments (2011)
Journal Article
Clark, S. J., Jouanna, P., Haines, J., & Mainprice, D. (2011). Calculation of infrared and Raman vibration modes of magnesite at high pressure by density-functional perturbation theory and comparison with experiments. Physics and Chemistry of Minerals, 38(3), 193-202. https://doi.org/10.1007/s00269-010-0395-y

Calculation of semiconductor band structures and defects by the screened exchange density functional (2011)
Journal Article
Clark, S., & Robertson, J. (2011). Calculation of semiconductor band structures and defects by the screened exchange density functional. physica status solidi (b) – basic solid state physics, 248(3), 537-546. https://doi.org/10.1002/pssb.201046110

Limits to doping in oxides (2011)
Journal Article
Robertson, J., & Clark, S. (2011). Limits to doping in oxides. Physical review B, 83(7), Article 075205. https://doi.org/10.1103/physrevb.83.075205

The chemical trends of limits to doping of many semiconducting metal oxides is analyzed in terms of the formation energies needed to form the compensating defects. The n-type oxides are found to have high electron affinities and charge neutrality lev... Read More about Limits to doping in oxides.

Screened exchange density functional applied to solids (2010)
Journal Article
Clark, S. J., & Robertson, J. (2010). Screened exchange density functional applied to solids. Physical review B, 82(8), Article 085208. https://doi.org/10.1103/physrevb.82.085208

Electron and vibrational spectroscopies using DFT, plane waves and pseudopotentials: CASTEP implementation (2010)
Journal Article
Milman, V., Refson, K., Clark, S., Pickard, C., Yates, J., Gao, S. -., …Segall, M. (2010). Electron and vibrational spectroscopies using DFT, plane waves and pseudopotentials: CASTEP implementation. Journal of molecular structure. Theochem, 954(1-3, SI), 22-35. https://doi.org/10.1016/j.theochem.2009.12.040

Understanding the optical spectroscopy of amphiphilic molecular rectifiers: A density functional approach (2010)
Journal Article
Tan, O., Clark, S., Szablewski, M., & Cross, G. (2010). Understanding the optical spectroscopy of amphiphilic molecular rectifiers: A density functional approach. The Journal of Chemical Physics, 133(24), Article 244702. https://doi.org/10.1063/1.3516177

We present results of first principles density functional theory calculations of the electronic and atomic structural properties of model Z-type Langmuir–Blodgett (LB) layers comprising amphiphilic quinolinium tricyanoquinodimethanide (Q3CNQ) chromop... Read More about Understanding the optical spectroscopy of amphiphilic molecular rectifiers: A density functional approach.

ELECTRONIC, MECHANICAL AND OPTICAL PROPERTIES OF Si(3)P(4) AND Ge(3)P(4): AN AB INITIO STUDY (2010)
Journal Article
Khan, G. G., Clark, S., & Bandyopadhyay, N. (2010). ELECTRONIC, MECHANICAL AND OPTICAL PROPERTIES OF Si(3)P(4) AND Ge(3)P(4): AN AB INITIO STUDY. International Journal of Modern Physics B, 24(28), 5487-5494. https://doi.org/10.1142/s0217979210055354

Intrinsic defects in ZnO calculated by screened exchange and hybrid density functionals (2010)
Journal Article
Clark, S., Robertson, J., Lany, S., & Zunger, A. (2010). Intrinsic defects in ZnO calculated by screened exchange and hybrid density functionals. Physical review B, 81(11), Article 115311. https://doi.org/10.1103/physrevb.81.115311

The formation energies of intrinsic defects in ZnO are calculated by a family of screened exchange and hybrid density functionals, which include different fractions of Fock exchange and range separation in the hybrids. All functionals improve on loca... Read More about Intrinsic defects in ZnO calculated by screened exchange and hybrid density functionals.

Role of Clay Minerals in Oil-Forming Reactions (2010)
Journal Article
Geatches, D. L., Clark, S. J., & Greenwell, H. C. (2010). Role of Clay Minerals in Oil-Forming Reactions. The Journal of Physical Chemistry A, 114(10), 3569-3575. https://doi.org/10.1021/jp9096869

Mineral-catalyzed decarboxylation reactions are important in both crude oil formation and, increasingly, biofuel production. In this study we examined decarboxylation reactions of a model fatty acid, propionic acid, C2H5COOH, to an alkane, C2H6, in a... Read More about Role of Clay Minerals in Oil-Forming Reactions.

Oxygen vacancy levels and electron transport in Al(2)O(3) (2010)
Journal Article
Liu, D., Clark, S., & Robertson, J. (2010). Oxygen vacancy levels and electron transport in Al(2)O(3). Applied Physics Letters, 96(3), Article 032905. https://doi.org/10.1063/1.3293440

The energy levels of the oxygen vacancy in α- and θ-Al2O3 were calculated using the screened exchange hybrid functional, and explain the electron hopping and trapping levels seen in deposited Al2O3 at ∼ 1.8 eV below its conduction band edge. The vaca... Read More about Oxygen vacancy levels and electron transport in Al(2)O(3).

Structural, electronic and vibrational properties of tetragonal zirconia under pressure: a density functional theory study (2009)
Journal Article
Milman, V., Perlov, A., Refson, K., Clark, S. J., Gavartin, J., & Winkler, B. (2009). Structural, electronic and vibrational properties of tetragonal zirconia under pressure: a density functional theory study. Journal of Physics: Condensed Matter, 21(48), Article 485404. https://doi.org/10.1088/0953-8984/21/48/485404

Evidence for hydrogen transport in deuterated LiBH(4) from low-temperature Raman-scattering measurements and first-principles calculations (2009)
Journal Article
Gremaud, R., Lodziana, Z., Hug, P., Willenberg, B., Racu, A., Schoenes, J., …Borgschulte, A. (2009). Evidence for hydrogen transport in deuterated LiBH(4) from low-temperature Raman-scattering measurements and first-principles calculations. Physical review B, 80(10), Article 100301. https://doi.org/10.1103/physrevb.80.100301

Energy levels of oxygen vacancies in BiFeO(3) by screened exchange (2009)
Journal Article
Clark, S., & Robertson, J. (2009). Energy levels of oxygen vacancies in BiFeO(3) by screened exchange. Applied Physics Letters, 94(2), Article 022902. https://doi.org/10.1063/1.3070532

The oxygen vacancy in BiFeO3 is calculated to be a double donor with states 0.6 eV below the conduction band edge, consistent with cathodoluminescence and electronic conductivity data. The atomic configurations were relaxed using the local density ap... Read More about Energy levels of oxygen vacancies in BiFeO(3) by screened exchange.

Moving AHEAD with an international human epigenome project (2008)
Journal Article
Jones, P. A., Archer, T. K., Baylin, S. B., Beck, S., Berger, S., Bernstein, B. E., …Excellence, E. U. N. (2008). Moving AHEAD with an international human epigenome project. Nature, 454(7205), 711-715. https://doi.org/10.1038/454711a

The Complex Excited-state Behavior of a Polyspirobifluorene Derivative: The Role of Spiroconjugation and Mixed Charge Transfer Character on Excited-state Stabilization and Radiative Lifetime (2008)
Journal Article
Hintschich, S. I., Rothe, C., King, S. M., Clark, S. J., & Monkman, A. P. (2008). The Complex Excited-state Behavior of a Polyspirobifluorene Derivative: The Role of Spiroconjugation and Mixed Charge Transfer Character on Excited-state Stabilization and Radiative Lifetime. Journal of Physical Chemistry B (Soft Condensed Matter and Biophysical Chemistry), 112(51), 16300-16306. https://doi.org/10.1021/jp8044884

In this study, we report on the unusual fluorescence decay of an alkoxy-substituted polyspirobifluorene. Excited state behavior has been probed as a function of time, using femtosecond photobleaching, single photon counting, and streak camera techniq... Read More about The Complex Excited-state Behavior of a Polyspirobifluorene Derivative: The Role of Spiroconjugation and Mixed Charge Transfer Character on Excited-state Stabilization and Radiative Lifetime.

Electronic defects in LaAlO3 (2008)
Journal Article
Xiong, K., Robertson, J., & Clark, S. (2008). Electronic defects in LaAlO3. Microelectronic Engineering, 85(1, SI), 65-69. https://doi.org/10.1016/j.mee.2007.01.181

β phase and γ-β metal-insulator transition in multiferroic BiFeO3 (2008)
Journal Article
Palai, R., Katiyar, R., Schmid, H., Tissot, P., Clark, S., Robertson, J., …Scott, J. (2008). β phase and γ-β metal-insulator transition in multiferroic BiFeO3. Physical review B, 77(1), Article 014110. https://doi.org/10.1103/physrevb.77.014110

We report on extensive experimental studies on thin film, single crystal, and ceramics of multiferroic bismuth ferrite BiFeO3 using differential thermal analysis, high-temperature polarized light microscopy, high-temperature and polarized Raman spect... Read More about β phase and γ-β metal-insulator transition in multiferroic BiFeO3.